This invention relates generally to handle apparatus and more particularly to a safety release handle for rotating a motor shaft on a stone grinding mill.
Small grinding mills for home use in grinding grains, rice and other kernel foods are becoming increasingly common. Some of the simpler mills are manually driven while other mills utilize an electric motor to drive the grinding stones. A motor is preferable because of the high rotational speeds needed for rapid grinding. However, motor driven mills are dependent upon an energy source and are useless in the event of a power failure.
In some instances, a handle has been provided to turn the shaft of a motor driven mill for manual operation. The handle must be mounted to grip the shaft tightly in order to impart torque to the shaft. If for some reason the handle is inadvertently left on the shaft when the motor is started, the handle is rapidly rotated with the shaft presenting a dangerous hazard for anyone nearby. In addition, the spinning handle may separate from the shaft causing damage to property and injury to the operator or bystanders.
The present invention is directed to a safety handle for manually turning the motor shaft of a stone grinding mill. One end of the handle connects to the shaft so as to grip the shaft tightly as torque is imparted in the direction of motor rotation. If the handle is rotated in the opposite direction, it automatically disengages from the shaft. Should the motor shaft begin to turn independent of handle operation, inertia and gravity will act upon the handle to effectively rotate the handle relative to the shaft opposite to the direction of normal motor rotation. Thus, the handle automatically disengages and falls from the shaft in the event of inadvertent motor start-up.
In accordance with one aspect of the invention, handle apparatus is provided for manually rotating a motor shaft in a predetermined direction. Grip means engage the shaft to apply rotational torque by a lever arm connected to the grip means. The grip means automatically releases the shaft when the shaft rotates independently in the predetermined direction. The lever is adapted to allow rotation with the shaft only when the grip means is engaged with the shaft for rotation in the predetermined direction.
In accordance with another aspect of the present invention, a handle apparatus is provided for manually rotating a motor shaft having an aperture therein. The handle includes a mechanism for gripping the shaft with a curved portion adapted to contact the periphery of the shaft and a projecting portion adapted for inserting into the aperture. The curved portion and the projecting portion engage the shaft when rotational torque is applied to the gripping mechanism in the first direction and disengage the shaft when rotational torque is applied to the gripping mechanism in a second direction. A lever integral with the gripping mechanism projects radially outward from the shaft for applying torque to the mechanism.
In accordance with yet another aspect of the present invention, an automatic release handle is provided for a grinding mill having an electric motor with a shaft projecting from the rear of the motor. A curved member engages a portion of the circumference of the shaft. A hook projects from one end of the curved member into a keyway in the shaft. A lever arm integral with the other end of the curved member extends radially from the shaft. The handle grips the shaft to impart torque to the shaft in the direction of normal motor rotation and disengages from the shaft upon independent rotation of the shaft in that direction.